Feather forensic expert Carla Dove makes a slide of a partially digested bird feather taken from the autopsy of a Burmese python in Florida's Everglades National Park. Park officials mailed the stomach contents of eight pythons to Dove's lab at the Smithsonian Museum of Natural History so she could identify the types of birds the pythons had eaten.

These partially digested specimens were cleaned, dried and labeled by the National Park Service in Florida and mailed to Dove's lab. The larger bag contains a python's ID number and is filled with smaller bags labeling each specimen.

Dove has a good sense of the species she may be looking for. She pulls out a limpkin (a cranelike bird that lives in Florida) from one of the many drawers in the museum's bird collection to compare its feathers with her sample.

Dove relies heavily on the museum's massive collection of birds to solve her feathered mysteries. The collection contains about 620,000 species from all over the world. The birds are organized alphabetically in drawers that reach floor to ceiling.

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Carla Dove smiles as she tears open a small, flat cardboard box. She is sitting at a lab bench in her office at the Smithsonian Museum of Natural History.

"It's kind of like Christmas for me because I never know what's going to be in the packages," she says.

Inside the box are a bunch of sealed sandwich-size bags. Dove counts the bags.

"Eight samples today," she notes. Each sample consists of grayish pieces of feathers, and sometimes bones, all from inside the stomachs and intestines of Burmese pythons.

Dove is an ornithologist and a forensic expert of sorts. But unlike most forensic scientists, who help identify perpetrators of crimes, Dove identifies victims. And the victims in this case are birds. From the skimpiest of remains — mere bone fragments and feathers — Dove often can trace the dead bird's species. The aviation industry relies on Dove to identify the birds involved in thousands of collisions between birds and planes every year.

Recently, she was called in to solve a different sort of murder mystery — applying her skills to figuring out which types of native birds are falling prey to the giant Burmese pythons now thriving in Florida's Everglades.

Park officials know the snakes are devouring rabbits, foxes, even alligators. They have sometimes caught the pythons in the act. In addition, scientists have documented declining populations of a range of mammals in the area, suggesting the big snakes may be slowly wiping them out.

But less is known about which birds these pythons have been snacking on. So park officials recently approached Dove for help. She gets to work, picking up one of the plastic bags, labeled "Python no. 780. (Collected on) March 18th, 2013."

"We can see what's in here and go to work and identify what birds this nasty python has been eating," says Dove.

Identifying the birds from their DNA is nearly impossible in these cases because the half-digested remains are contaminated with snake DNA. Instead, Dove concentrates on subtle distinctions among feathers.

"Sometimes they are nice and complete feathers and I can recognize them right away," says Dove. But often, she has only tiny fragments to go on. Like the one she pulls out from the bag with the help of tweezers.

"Even though it's as tiny as a strand of hair really, it can be enough to have some special diagnostic microscopic features to help us determine if it's a heron or maybe it's a bird of prey or a pigeon or a dove," she explains.

The piece she holds is a downy bit from the base of a feather. It contains tiny branches called barbules. Dove gently places it on a glass slide, and turns on her microscope.

"I'll let you have a look at this," she says. "In the middle of the slide there's a tiny piece of a downy barbule that has me excited."

All I see are abunch of fine, transparent needles with bits of color here and there. But Dove recognizes the pattern instantly. It belongs to a group of birds that includes cranes and rails. This bird, though, is different from the other birds in that group, Dove says. She suspects the python's victim was a limpkin.

Forensic Ornithology Gets Its Start

The field of forensic ornithology had its start in 1960, when a flock of starlings brought a passenger plane down in Boston Harbor. The crash destroyed the plane and killed most of the people onboard.

The airline — Eastern Airlines — sent the bird remains to an ornithologist named Roxie Laybourne at the Smithsonian Museum. Laybourne identified the flock as starlings, and from then on she became the go-to person for an airline industry trying to solve bird-strike cases. (She would later become Dove's mentor.)

"After the Boston crash, that's when the airlines industry started to get really interested in birds that are causing damage to airplanes," says Dove.

Most such strikes don't cause crashes, but it's still really important to know which species was involved, Dove says, so you can try to change the flight path, or alter the airport environment or design stronger aircraft engines.

And there's a huge demand for Dove's expertise. Just this past year, she processed about 8,000 cases, many of them involving military airplanes.

"We get a lot of samples from Afghanistan," Dove says. A few years ago, she solved the mystery of a large unknown bird that flew into a fighter jet at Bagram air base.

"There was several million dollars' worth of damage," says Michael Begier, the national coordinator for the Airports Wildlife Hazards Program at the U.S. Department of Agriculture. He was called in by the Air Force to help with this case.

Dove had identified the offending bird as a black kite.

"The black kite is a raptor, but it's similar in size to some of the vulture species we have in North America," says Begier. It was up to Begier and his team to prevent such accidents from happening again. So they went out to Bagram air base and started looking for black kites.

"One of the things we discovered is that trash disposal at the base was in a spot that brought the birds closer to the runway and the flight paths of the jets," he says. Once the trash was removed, the birds disappeared.

The Story Of Python No. 780

Dove is able to identify birds from anywhere in the world, in part because the Smithsonian Museum has a massive collection of birds.

She takes me out into a climate-controlled hallway, stacked from floor to ceiling with wooden cabinets.

"This collection is like my library ... my reference," she says. The library has 620,000 specimens from around the planet. Dove's work with the military in Afghanistan alone has added 80 new species to the museum's collection.

But it's the python victims that are on her mind today. She wants to confirm that the fragment she saw under the microscope was indeed from a limpkin, and she's in luck — in addition to the fragment, the plastic bag also contained a single intact feather.

"Here we go to the limpkin drawer," says Dove, as she walks up to one of the cabinets. She slides off the door and pulls out one of the drawers.

Inside are a bunch of very still, very dead birds that look something like a crane, all brown in color with lots of white specks.

Dove holds the single feather from the sample against the wing feathers of one dead bird. The match is perfect.

"I think we have solved this case!" she declares. "Python No. 780 was feasting on a limpkin on 18th of March, 2013."

In all, Dove has examined the remains of nearly 150 Burmese pythons. She has found that they snack on some 30 species of birds, including limpkins, mallards, egrets, herons and wood storks.

A Dying Field?

Dove's keen eye and knowledge of feathers have come from more than two decades of practice. She's the only person in the country with these skills, and she worries about the future of this kind of analysis.

"Unless I have someone to follow me around, and do some research on the microscopic structure of feathers, I think that one of these days the whole expertise in this field is going to go away," she says. These days, she says, students are more interested in "instant satisfaction" and cutting-edge technology.

Dove inherited her lab from the only other U.S. scientist to do this work: Laybourne, who was already in her 80s.

Dove says she has yet to find the person who will take over when she retires — the special ornithologist who can continue the work in this unusual feather forensics lab.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

DAVID GREENE, HOST:

And now a murder mystery of sorts. The scene of the crime: Everglades National Park. We already know the murderer: the giant Burmese python. The species has invaded Florida. The mystery lies in identifying its victims. As NPR's Rhitu Chatterjee reports, a forensics expert is on the case.

(SOUNDBITE OF BOX TEARING OPEN)

RHITU CHATTERJEE, BYLINE: Carla Dove opens a small white box. She's sitting at a lab bench in her office at the Smithsonian Museum of Natural History.

CARLA DOVE: It's kind of like Christmas for me because I never know what's going to be in these packages.

CHATTERJEE: Inside are a bunch of sandwich-size Ziploc bags.

DOVE: One, two, three, four, five, six - eight. Eight samples today.

CHATTERJEE: Each sample consists of grayish pieces of feathers, and sometimes bones, all from inside the stomachs and intestines of Burmese pythons. These giant snakes are thriving in the Everglades and devouring local birds and animals.

DOVE: Let's look at this one first. This is python number 780. It was collected on the 18th of March 2013, so it's a recent one.

CHATTERJEE: Park officials are interested in the diets of these pythons because they want to know what native species might be threatened. Now, when it comes to animals, they pretty much know that the snakes eat rabbits, foxes, even alligators. They've often caught them in the act. But it's been harder to know what birds they've been snacking on. That's where Carla Dove comes in.

DOVE: We can see what's in here and go to work on identifying the birds that this nasty snake has been eating.

CHATTERJEE: Now, you can't identify the birds from their DNA because these half-digested remains are contaminated with snake DNA. So it's a question of recognizing the birds just from their feathers.

DOVE: Sometimes they are nice and complete feathers and I can recognize them right away.

CHATTERJEE: But often she has only tiny fragments to go on. She uses tweezers to pull a piece out from one of the Ziploc bags.

DOVE: Even though it's as tiny as the strand of hair, really, it could be enough to have some special diagnostic microscopic features that might help us determine if it's a heron or maybe it's a bird of prey or a pigeon or a dove.

CHATTERJEE: This piece is a downy bit from the base of a feather, what scientists call barbules. Dove places it gently on a glass slide and turns on her microscope.

DOVE: I'll let you have a look at this. In the middle of this slide there's a tiny piece of a downy barbule that has me excited.

CHATTERJEE: To me it's just a bunch of fine transparent needles with bits of color here and there. But Dove recognizes the pattern instantly. It belongs to a group of birds that includes cranes and rails. But...

DOVE: It's different from the rest of the birds that it's related to.

CHATTERJEE: She still has to confirm it, but she suspects the python's victim was a limpkin. Now, most days Dove spends her time investigating the remains of birds who've died in very different circumstances: birds who've crashed into airplanes, like the flock of starlings that brought down a flight off of Boston Harbor back in 1960. The crash destroyed the plane and killed most of its passengers.

DOVE: After the Boston crash, the airline industry started to get really interested in birds that are causing damage to airplanes.

CHATTERJEE: Most bird strikes don't cause crashes, but it's still really important to know what species was involved, so you can change flight paths or alter the airport environment or design stronger aircraft engines.

DOVE: Knowing the exact species of bird that is on your airfield and causing a problem is the very first step in trying to reduce this risk.

CHATTERJEE: And there's a huge demand for Dove's expertise. Just this past year, she processed about 8,000 cases, many of them involving military airplanes.

DOVE: We get a lot of samples from Afghanistan. That's because we're doing a lot of flying there.

CHATTERJEE: A few years ago, she solved the mystery of a large unknown bird that flew into a fighter jet at Bagram Air Base. Michael Begier is with the U.S. Department of Agriculture's Airport Wildlife Hazards Program. He was called in by the Air Force to help with the case.

MICHAEL BEGIER: There was several million dollars' worth of damage.

CHATTERJEE: Dove had identified the offending bird as a black kite.

BEGIER: The black kite is a raptor, but it's similar in size to some of the vulture species we have in North America.

CHATTERJEE: And it was up to Begier and his team to prevent such accidents from happening again. So they went out to Bagram Air Base and started looking for black kites.

BEGIER: One of the things we discovered was that trash disposal at the base was in a spot that brought the birds closer to the runway and to the flight path of the jets.

CHATTERJEE: Once the trash was removed, the birds disappeared. One of the reasons Dove is able to identify birds from anywhere in the world is because the Smithsonian Museum has a massive collection of birds. Dove takes me out into a climate-controlled hallway, stacked from floor to ceiling with cabinets.

DOVE: So this collection is like my library. This is my reference.

CHATTERJEE: The library has 620,000 specimens from all over the world. And in fact, Dove's work with the military in Afghanistan has added 80 new species to the museum's collection. But it's the python victims that are on her mind today. She wants to confirm that the fragment she saw under the microscope was indeed from a limpkin.

DOVE: Here we go to the limpkin drawer. Slide out the case door.

CHATTERJEE: She's in luck, because in addition to that fragment, the ziplock bag also contained a single intact feather. She holds it against the wing feathers of a very still, very dead bird that looks a bit like a browner, smaller version of a heron. The match is perfect.

DOVE: So I think we have solved this case. Python number 780 was feasting on a limpkin on 18th of March 2013.

CHATTERJEE: Dove's keen eye and knowledge of feathers has come from more than two decades of practice. And she's the only person in the country with these skills. But she worries about the future of this kind of analysis.

DOVE: Unless I have someone to follow me around and do some research on the microscopic structure of feathers, I think that one of these days the whole expertise in this field is going to go away.

CHATTERJEE: She inherited this lab from the only other person in the country who did this kind of work. But she says she has yet to find the person who will take over this unique feather forensics lab. Rhitu Chatterjee, NPR News, Washington.

(SOUNDBITE OF MUSIC)

GREENE: The aptly named Carla Dove has determined that pythons like to snack on some 30 species of birds, including limpkins, mallards, egrets, herons and wood storks. To date, Dove has examined the remains on nearly 150 Burmese pythons. You can learn more about her work and also take a virtual tour of her lab by watching a slideshow at NPR.org. Transcript provided by NPR, Copyright NPR.